In recent years, audio signal control devices that control two audio signals simultaneously with a sliding member sliding between both ends A and B of a sliding range have been known (e.g., Patent Document 1). Such audio signal control devices are generally called “crossfaders”; the volume of a first sound increases as the sliding member slides from the end A to the end B; on the contrary, the volume of a second sound increases as the sliding member slides from the end B to the end A. In other words, the mixing rate of two audio signals may be determined with one interface according to the position of the sliding member. Especially, often applied in DJ equipment (equipment used by disc jockeys [DJs] for acoustic performances) that is used in clubs or other venues, such audio signal control devices are expected to be easier to operate.    [Patent Document 1] JP-A-2004-005987
On the other hand, such audio signal control devices are applied to video signals nowadays; control devices that are capable of determining the mixing rates of two video signals with one interface are also known. Often applied in VJ equipment (equipment used by visual or video jockeys [VJs] for video performances) that is used to display diversified video images on monitors in clubs or other venues, such video signal control devices are expected to be easier to operate as well as such DJ equipment.